The key arrangement, or layout, of keyboards used in different geographical areas around the world varies based on language. For example, typists in the United States typically learn to use QWERTY keyboards. In this regard, FIG. 1 illustrates an exemplary physical QWERTY keyboard 10 comprised of physical keys 12, each key 12 corresponding to a character in the English language. FIG. 2 illustrates an exemplary software QWERTY keyboard 22 provided in software to provide virtual keys 24 on a display 26 of an electronic device 28. For example, the electronic device 28 may be a touch-screen computing pad or other computing device where keypresses on the virtual keys 24 are sensed by touch. Similar keyboards can be provided for other languages. For example, a German-speaking typist may use a QWERTZ keyboard. A French-speaking typist may use an AZERTY keyboard.
Through practice, typists may develop typing proficiency and speed with a keyboard having a particular layout. Typists develop “procedural memory” of finger movement patterns associated with typing a vocabulary of phrases, words, and characters. Procedural memory is the type of physiological memory used by humans to perform certain actions without consciously thinking about them, for example, riding a bicycle, driving a manual transmission vehicle, performing a song on a piano or other instrument, or typing a vocabulary of phrases, words, and characters. In this regard, referring to FIG. 1, a typist may be trained to position her fingers on home keys 14, 16 which may be located on a home row 18, 20 of the physical QWERTY keyboard 10. To type an individual character, a typist may learn which finger should be moved to type the character (i.e., which finger should be activated) as well as a direction and distance to move the finger relative to a home finger position. To type a word or phrase, the typist may develop procedural memory associating a pattern of finger activations and movements (relative to home finger positions) to type the word or phrase. Thus, procedural memory aids one in becoming efficient at rapid text and data entry on keyboards whose key layouts conform to one's prior training. Once a certain keyboard's key layout has been learned by a typist and committed to procedural memory, the typist may poorly tolerate switching to a keyboard with an alternative key layout.
To support a more mobile workforce and lifestyle, electronic devices are increasingly becoming more compact and more portable. These electronic devices commonly include a keyboard with either physical keys or virtual keys, such as the physical keys 12 or the virtual keys 24 in FIGS. 1 and 2 as examples, to allow a typist, or user, to input data and provide commands or other inputs. Certain user applications (e.g., email clients) developed for these electronic devices may require extensive text and data entry. A full-size keyboard facilitates rapid text and data entry, but may require a key layout that is too large to incorporate into a compact electronic device. Furthermore, there may be a tradeoff in the amount of area designated for input on an electronic device versus the amount of area designated for a display. Even on virtual keyboards that allow providing virtual keys on the display without providing a separate input area, the size of the keyboard may constrain the area of the screen available for displaying other information, such as other inputs or output.
One approach to reducing keyboard size is to shrink the size of the keys. However, as key sizes are reduced, typists lose the ability to locate all their fingers upon a home row and may resort to using a single finger (such as a thumb or index finger) of one or both hands for data entry. Very small keys may even be difficult to accurately press with a single finger. In addition, when interacting with such miniature keyboards, typists are unable to make use of the procedural memory they previously developed using full-size keyboards. Instead, users must retrain themselves to use different finger patterns to press the keys.
Another approach to reducing keyboard size is to reduce the number of keys of the keyboard by allowing several characters to occupy a same key. Such a key may unambiguously represent the several characters, for example, when pressed in combination with a modifier key (e.g., Ctrl, Alt, Shift, Fn, or Cmd), or when pressed multiple times in succession (to cycle through the several characters). Alternatively, a key may be overloaded to represent several characters ambiguously. In this scenario, when overloaded keys are pressed, disambiguation software can be employed to determine which corresponding characters are intended, for example, based on dictionary matching, word and letter frequencies, and/or grammar rules. However, where the layout of a reduced-size, overloaded keyboard does not readily conform to a user's previously learned typing procedures, user retraining may be difficult or time-consuming, and adoption of such devices may be poorly tolerated by users.